246 



FUNDAMENTALS OF FRUIT PRODUCTION 



perate regions, but . . . shows a rise as development proceeds. . . . We 

 learn too from the art of fruit forcing that we must regard the rise not as 

 constant but as oscillating." He cites Pynaert in giving the tempera- 

 tures shown in Table 9 as most favorable in forcing the peach. At two 

 periods the temperature is lowered. Ward ^^i in England and Schneider^^^ 

 in northwest Europe differ somewhat in detail from this temperature 

 statement; Schneider indicates a lowering of temperature at the time of 

 stoning. 



Table 9. — Optimum Temperatures in Forcing the PeachI'" 

 (Degrees Centigrade) 



Day temperature 



Night temperature 



First week 



Second week 



Third week 



To flowering .... 



At flowering 



After flowering . . 

 During stoning . . 

 After stoning. . . 

 At fruit ripening 



9 to 10 

 10 to 12 

 12 to 15 

 15 to 18 



8 to 12 



15 to 18 

 12 to 15 



16 to 19 

 20 to 22 



5 to 7 

 7 to 9 

 9 to 11 



11 to 14 



6 to 10 



11 to 14 

 9 to 11 



12 to 15 

 15 to 17 



Variation in Quality with Amount of Summer Heat. — The fruit 

 which has received the most careful study in its relation to temperature 

 conditions is the grape. Blodgettj^" writing in 1857, when grape growing 

 in America was in an experimental stage, predicted very closely, from 

 climatological data, the geographic distribution of the industry in the 

 United States. 



Boussingault^^ early remarked on the variation in yield and quality of wine 

 of a vineyard in Flanders, the variation depending on the temperature of the 

 growing season, and reported data shown in Table 10. Baragiola,'^ taking succes- 

 sive samples of grapes through two autumns, found a striking correspondence 

 between sugar increase and temperature, regardless of the stage of ripening at 

 which the low or high temperatures occurred. A brief period of warm weather 

 late in the season compensates apparently to a considerable degree for earher 

 deficiencies : a brief period of cool weather at the same stage apparently goes far 

 to nullify previous favorable conditions. Heat requirements for grapes during 

 the growing season can be understood best from European experience since the 

 climatology of this fruit has been studied most extensively there and is to a 

 considerable degree free from the compUcation of winter temperature limitations. 

 Boussingault22 considered that the mean temperature of the growing season 

 must be at least 59°F. and of the summer 65° to 67°F. to produce Vinifera grapes 

 satisfactorily. In some of the equatorial table lands of South America, he 

 states, where the mean temperature is 62° to 66°F. with little range, though the 



